Eclipse 400-029 is a Outlet Tester - Standard outlets. It is also known as AC Receptacle Tester. This is used to check if the outlet is wired correctly and if a ground is present, but not the quality of the ground.

Receptacle Tester - Standard
Checks if the outlet is wired correctly and if a ground is present

Eclipse 400-029 Outlet Tester - Standard outlets

Checking if the outlet is wired correctly and if a ground is present